Robinia `Purple Crown`

ABSTRACT

A seedling discovered growing in a cultivated area in a row of seedlings resulting from a cross between Robinia hispida, and Robinia pseudoacacia, and noticed because of its more vigorous, narrow upright crown of branches, and particularly at the time of blooming for its abundant purple pea-shaped flowers.

BACKGROUND OF THE DISCLOSURE

As a hybridizer, and grower of many different plants during theoperation of a commercial nursery, I have been particularly careful toobserve various decorative plants and particularly trees which I feelhave decided commercial appeal.

As this suggests, when I find new varieties of plants each of which havesome attraction which I deem outstanding, or which suggest thatimprovement of each may result from crossing them, I have caused that tobe done, usually resulting in a new cultivar which is commerciallyappealing.

This naturally results because of improved characteristics where I havehad an opportunity to observe the parent plants and have reason tobelieve a cross would result in a plant which my nursery would grow andsell to others.

SPECIFIC DESCRIPTION OF THE DISCLOSURE

This particular invention relates to a new hybrid of Robinia, which wasdiscovered as a seedling in a row of seedlings of Robinia hispida, beinga cross with Robinia pseudoacacia.

Continued observation over time disclosed that the seedling was morevigorous growing with a narrow and upright crown of branches. Later whenthe seedling came into bloom it proved to be abundant flowering, bearingthousands of pendulous racemes of purple pea-shaped flowers having amild fragrance.

As is customary in the nursery in which I carry on breeding anddevelopment of flowering trees and other decorative plants, I havecaused my new hybrid which I have chosen to call `Purple Crown`, to beasexually propagated by grafting on bare root understocks, observingthat the same comes true in successive generations and is in my judgmentan attractive, decorative plant for many different types of display.

In continuing observation of successive generations of this new hybrid,I note that it is almost thornless on mature branches.

As to its form, my new hybrid may be described as intermediate betweenthe parent species.

When compared with R. hispida, which is a spreading shrub about 1.5 m.tall with bristley twigs and R. pseudoacacia which is a tall and narrowtree up to 20 m. tall with thorny twigs, my hybrid is intermediate.

During a long period of growth and observation of my new plant, I havenoted that it is tolerant of hot and dry weather and also of soilshaving high pH. content.

In observing the growth rate of my new hybrid and using a one year termas a basis, I have found that the average height at the end of the firstsummer's growth is between 1.5 and 2.0 meters.

Sister seedlings over the same time period attain average height of 1.3to 1.6 meters.

Robinia pseudoacacia may be expected to reach heights of 2.3 to 2.6meters in that time.

By comparison Robinia hispida may average a height of 0.5 to 0.7 metersover the same time.

My new plant does not appear to be susceptible to diseases which may bepeculiar to Robinia in general, and it has been found that in years withhot summers when Robinia pseudoacacia clones such as `Frisia`(unpatented) and `Umbra culifera` show marginal heat scorch on theleaflets, my new variety is unharmed.

My new variety has not exhibited leaf chlorosis in soils with a pH ashigh as 7.5.

Breeding and growing of my new variety have taken place in the vicinityof Plainsboro Township, Middlesex County, N.J.

Specific characteristics of my new hybrid are summarized in thefollowing, and where reference to color is made the drawing discloses in

FIG. 1, a view of a tree of my new hybrid.

FIG. 2 is a detailed view of my hybrid to show the shape and color ofthe flowers on one of the racenes.

The color notations are made from comparison with the Munsell Color Fan,noting that the colors are as nearly true as it is possible to make thesame in photographs of which the figures are examples.

DETAILED DESCRIPTION OF THE INVENTION

Parentage:

Seed parent.--Robinia hispida.

Pollen parent.--Robinia pseudoacacia.

Tree: Small; upright; dense and hardy.

Trunk.--Slender; rough.

Branches.--Slender; smooth with minute paired thorns beside the nodes.Color -- Moderate brown, 5 YR 3/3. Lenticels -- Moderately abundant,minute. Number -- 15 to 17 per square cm. of twig surface.

Leaves.--Moderately abundant; compound; medium thickness. Length -- 18to 24 cm. Width -- 12 to 13 cm. Shape -- Compound; 12 to 14 leaflets,each leaflet 6 cm. long, 3.5 cm. wide. Color -- Moderate olive green,7.5 G.Y. 4/4. Margin -- Smooth edge leaflets. Petiole -- Short; 4 to 5cm. long. Glands -- None.

Flower buds.--Very hard; minute.

Flowers: Borne in pendulous racemes 15 to 18 flowers per raceme.

First bloom.--May 20.

Full bloom.--May 24.

Quantity.--Abundant; mildly fragrant.

Size.--Medium.

Petalage: Pea-shaped flowers, calyx campanulate, standard sub-orbicularand reflexed, keel incurved its petals united below.

Shape of petals.--Pea-shaped; 5 petals. Size -- Length 2.1 cm. Width 2.5cm.

Color.--Strong reddish purple 2.5 RP 5/10.

Fruits: Pods lightly hirsute, 4 to 6 cm. long, rarely borne, 1 to 3seeds.

Abundance.--Very sparse.

Size.--Pods 4 to 6 cm. long.

Color.--Moderate brown.

I claim:
 1. A new and distinct Robinia hybrid as described and illustrated characterized as to novelty by the vigorous growth, with narrow more upright crown of branches than either parent, the abundant flowering resulting in pendulous racemes of purple pea-shaped flowers with mild fragrance, nearly thornless when branches are mature, and its tolerance of heat, drought and high pH soils. 